The present invention relates to a panel sawing machine. The invention can be used in particular, but not solely, to cut panels, slabs or sheets made especially of wood-based materials but also of plastic, light metal alloys, steel and composite and mineral-bonded board, in order to form smaller boards.
The invention applies in particular to machine for sawing wood-based materials and comprising a horizontal table on which a movable device, usually known as pusher, can push at least one panel to a device downstream for sawing (or rotating) the panel, where, during the sawing operation, the panel is positioned by suitable pickup elements which grip the rear edge of the panel, and including any additional positioning, aligning, outfeed, pressing and rotating elements that constitute the standard equipment of these machines.
Known machines of this kind are normally equipped with a plurality of pickup elements, for example of the gripper type, mounted side by side in a given direction at right angles to the forward (or reverse) feed direction of the panels and acting on the rear edge of the panels to be cut.
These known panel sawing machines are used to cut panels of various sizes, both in width and length, usually placed one over the other in normally large stacks whose dimensions depend on the size of the panels made by the panel forming machines.
Conventional panel sawing machines may be of the simple type, with a single cutting axis, called lengthways axis, located downstream of the pusher, or more complex, with two (or more) cutting axes at an angle to each other and with panel feed tables positioned at 90xc2x0 to each other. In these more complex machines, the cutting axes ate downstream of the corresponding pushers, the first axis being called the lengthways axis and the second, the crossways axis.
In these known machines, the same pusher can also be used to saw two or more stacks of panels or boards in succession. In addition, stacks of different sized boards placed side by side can only be sawn simultaneously if the cutting line of the different stacks corresponds with the machine cutting axis concerned (creating what is usually known as a logical cutting pattern). If the cuts are not consistent (creating differentiated cutting patterns) several pushers may be provided, each acting on one (or more) board/boards or portion of panel and resulting in constructional complications and additional costs for the entire machine.
Depending on the size (whether initial or derived from pre-cuts) of the stack of panels or group of boards to be sawn, the machine must be equipped with a suitable number of pickup elements appropriately positioned and distributed along the entire rear edge of the related stack or group of boards so as to firmly hold the panels along the entire width and to line them up securely against a stop surface during the sawing operation.
One of the disadvantages of known panel sawing machines is that all of them are set up and equipped to cut a limited number of sizes of panel stacks or groups of panel stacks. This is accomplished by mounting on the pusher crossbeam a variable number of pickup elements or grippers, depending on the requirements of the end user. In other words, the manufacturer equips the pusher crossbeam with a number of pickup elements or grippers, variously distributed along the length of the beam, at fixed positions, using the smallest number of elements possible in order to reduce costs.
These machines are therefore rather inflexible in terms of size changeover and hence are not suitable for cutting panels of many different sizes unless fitted with complex equipment, which considerably raises construction costs and requires expensive tooling; not to mention the fact that, although machines of this kind are long-term investments, its capabilities are unable to satisfy process requirements after many years in operation, not least because of the diverse and constantly changing market requirements.
The present invention has for its principal object to overcome the disadvantages of prior art by providing a panel sawing machine, with either one or two (or more) cutting axes, that can be adjusted in an extremely simple and practical manner to work on panels or boards or groups of boards of any size.
One advantage of the present invention is that it permits two or more panels and/or boards in stacks placed side by side to be cut lengthways or crossways (depending on which machine axis is being used) even if the adjacent panels and/or boards must be sawn into smaller boards or panels differing in length and width from one panel or board to the next.
Another advantage is that it provides a machine that can be used to make boards of various sizes both in width and length with a relatively small number of cutting operations and allowing considerable saving of time.
The above mentioned aims and advantages are all achieved by the present invention as characterized in the claims below.